New Gears

**critten1** · 08-01-2007, 08:31 PM

I went to lunch with a friend of mine today. He has a 2007 Mustang GT and just changed his rear gears from the stock 3.38 to 3.73. Without adding horsepower, his car went from OK performance to kick butt for a couple of hundred dollars

.

Since the Diablosport Q&A thread says that we would be able to change gears out of the box (this was what was used on my friend's Mustang), does anyone know if anybody is considering manufacturing new gears for the LX platform?

I figure to get the same kind of kick that my friend got, you are looking at gearing about 10% higher than the 3.58 the LX cars come with stock. Say about 3.92. I'll stop there because if I try to go any deeper on gear ratios, I'll be talking through my you know what

Is this something that a small shop with a CNC can do, or will we have to wait for a big shop to get interested?

**Super T** · 08-01-2007, 09:00 PM

Gear design is voodoo... you're going to want a big player involved. Tooling for them is also expensive :-( Hopefully the suppliers have just been waiting on a tuning solution and have kicked around some R&D already. They'll certainly sell enough to make it worth their while!

**aries4life** · 08-01-2007, 09:02 PM

3.58???

Dude, we're in the 2.81 part of the world.

We need about a 3.2 gear in the rear to make things groovy.

**Pigman 440** · 08-01-2007, 09:34 PM

Where did the 3:58 figure come from?? Wish I had a 3:58!!

**critten1** · 08-01-2007, 09:37 PM

Originally Posted by Super T

Gear design is voodoo... you're going to want a big player involved. Tooling for them is also expensive :-( Hopefully the suppliers have just been waiting on a tuning solution and have kicked around some R&D already. They'll certainly sell enough to make it worth their while!

Keeping my fingers crossed.

2.81? I think my Dad's old Delta 88 had a better axle ratio than that!

**critten1** · 08-01-2007, 09:50 PM

Originally Posted by Pigman 440

Where did the 3:58 figure come from?? Wish I had a 3:58!!

Pulled the wrong number. Was looking at first gear ratio.

I saw these axle ratios listed on another web site:

Base: 2.87
RT: 2.82
SRT8: 3.06

2007 RT AWD: 3.07

**hemiuberalles** · 08-01-2007, 10:57 PM

I put a 3.73 under my '66 New Yorker 440. It made the damdest stop light dragger but couldn't pass a gas station.

**Super T** · 08-01-2007, 11:18 PM

Originally Posted by hemiuberalles

I put a 3.73 under my '66 New Yorker 440. It made the damdest stop light dragger but couldn't pass a gas station.

That's just it, we'll be dipping down into the single digits if we push it too far.

**lafrad** · 08-01-2007, 11:22 PM

well, MDS will keep a 3.73 gear in the mid-20's.

I wouldn't mind a mid to high 3.xx gearset... Go in the rear end with a quaife... it would allow me to be in MDS to and from work without hitting 8cyl... and also get me to the end of the 1/4 at 6500 in 3rd gear....

**GotMe-N-R/T** · 08-01-2007, 11:46 PM

Excuse me for my ignoance but can anyone explain to me or know of a link that would explain, "Gear Ratios"?

**Super T** · 08-01-2007, 11:57 PM

Originally Posted by GotMe-N-R/T

Excuse me for my ignoance but can anyone explain to me or know of a link that would explain, "Gear Ratios"?

Say you're holding the engine speed constant. The higher the rear gear ratio, the higher the torque at your rear wheels, but the slower they will go. So, big gear ratios make for fast launches but high rpm's and lower gas mileage.

**aries4life** · 08-02-2007, 08:16 AM

When you're comparing rear end gear ratios between different cars - you need to take into account the tranny ratios. We have a 5 speed with good spacing. I was under the impression that our ratios were close to that of most sparts cars. If we go too far 1st gear becomes useless. What would a mid-to-high 3.xx do to our first gear?

**8valves** · 08-02-2007, 09:31 AM

I'm fairly certain there is no room in the current center section for a better gear. You're simply out of space for the size of the ring gear to be increased at all.

Unless someone comes up with a new rear third member case and all, I think we're SOL. Looks like tire size is the only way to play with gear ratio for now, and even then it's going to take some dramatic changes to get the ratio people want.

Also someone mentioned it's a voodoo science. This is very true. Mustang's pick up because they're not the heaviest cars in the world (not the lightest either) but they have a fairly top end oriented powerband w/ the new Mod motors. They're trannies are geared strong for 1 and 2, but as soon as they hit 3rd the fun is done. A 3.73 swap changes this into really fast 1 and 2, and 3rd and 4th are now usable and enjoyable gears.

How many LX's out there have picked up from changing tire size to accomodate gears? And before someone answers that, be sure to take into consideration rotational mass losses of a smaller/lighter wheel/tire combo. Especially if it's a drag radial car and now they're cutting 1.8's as opposed to 2.0's, and a drag radial is a FAR lighter style of tire.

I'm curious, post up!

**Super T** · 08-02-2007, 09:36 AM

Originally Posted by 8valves

Also someone mentioned it's a voodoo science. This is very true.

Ha... I meant the actual design of the gears themselves. There's about a billion variables to consider and the end result is always a compromise. Picking the ratio is also a compromise, but you know upfront what your options are and what the outcome will be.

Personally I was only really excited about a rear gear when it was supposed to accompany the 6-speed manual